<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, 
        initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin:0;
            padding:0;
        }
        .box {
            width:375px;
            height:100px;
            background-color:pink;
        }
        .box1 {
            width:1px;
            height:1px;
            background:red;
        }
    </style>
</head>
<body>
    <div class="box">

    </div>
    <div class="box1"></div>
</body>
</html>